The overall objective of this project is to investigate the mechanism by which gonadotropins regulate the corpus luteum function. A model system has been developed by trypsin and collagenase of ovarian tissue to obtain single cell suspension in which the binding of labelled gonadotropin, cyclic AMP formation and progesterone synthesis can be demonstrated. The results suggest that the initial event in the hormone action is the binding of hormone to its receptor on the outer cell membrane followed by the formation of cyclic AMP which control steroidogenesis through processes sensitive to puromycin and actinomycin D. In addition, the binding of hormone to its receptor and/or activation of adenylate cyclase may be regulated by membrane bound protein kinase and phosphorprotein phosphatase whereas, the cytosol protein kinase may be involved in the translational processes by phosphorylation of ribosomes.